Traffic Signals on SH 121 are under the jurisdiction of the City of Plano. Please contact the City of Plano at (972) 941-7000 to report problems or concerns.

The Transportation Division continually evaluates each current and proposed signalized intersection to determine the safest and most efficient mode of operation based on standards specified by the Texas Manual on Uniform Traffic Control Devices. Even after a traffic signal is installed, all of the potential concerns at an intersection may not be addressed. For example, Dallas Parkway south of Main Street carries as many as ten times more vehicles than the streets that it intersects. Because of this large imbalance in traffic volumes, motorists on the intersecting streets may experience long waits at the signals to keep the traffic on Dallas Parkway flowing at an acceptable rate.